Cooling device

ABSTRACT

A cooling device includes first heat pipes thermally connected to a first heat-generating element at one end and thermally connected to the superimposed first and second heat-radiating fin groups at another end; and second heat pipes thermally connected to a second heat-generating element at one end and thermally connected to the superimposed second and third heat-radiating fin groups at another end, wherein the respective another ends of the first heat pipes altogether span a substantially entirety of a planar area between the first and second heat-radiating fin groups, and the respective another ends of the second heat pipes altogether span a substantially entirety of a planar area between the second and third heat-radiating fin groups.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to a cooling device that cools aheat-generating element.

Background Art

The increase in higher functionality of electronic devices has led toheat-generating elements, such as electronic components, being installedat high densities inside the electronic devices. Moreover, the amount ofheat generated by each electronic component etc. varies widely dependingon the difference in function of the electronic components etc.Accordingly, in order to reliably and efficiently cool theheat-generating elements, it is required to have uniform cooling of aplurality of heat-generating elements that generate differing amounts ofheat, even if the amount of heat generated is large.

To that end, Patent Document 1 proposes an electronic device including aheat sink for cooling a first heat-generating component, a first heatpipe thermally connecting the first heat-generating component to theheat sink, and a second heat pipe having a first end that thermallyconnects to a second heat-generating component and a second end that ispositioned in the vicinity of the heat sink.

Patent Document 1, however, is problematic in that the second heat pipeis separated from the heat sink and does not uniformly cool the firstheat-generating component and second heat-generating component.

RELATED ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Application Laid-Open Publication No.2008-130037

SUMMARY OF THE INVENTION

In view of the above-mentioned situation, the present invention aims atproviding a cooling device with excellent uniform cooling for aplurality of heat-generating elements that generate differing amounts ofheat. Accordingly, the present invention is directed to a scheme thatsubstantially obviates one or more of the problems due to limitationsand disadvantages of the related art.

Additional or separate features and advantages of the invention will beset forth in the descriptions that follow and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims thereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, in oneaspect, the present disclosure provides a cooling device, including: afirst heat pipe having one end thermally connected to a firstheat-generating element and another end thermally connected to a firstheat-radiating fin group that has a plurality of first heat-radiatingfins and a second heat-radiating fin group that has a plurality ofsecond heat-radiating fins; and a second heat pipe having one endthermally connected to a second heat-generating element that is disposedcloser to the second heat-radiating fin group than the firstheat-generating element and another end thermally connected to thesecond heat-radiating fin group and a third heat-radiating fin groupthat has a plurality of third heat-radiating fins, wherein the firstheat-radiating fin group, the second heat-radiating fin group, and thethird heat-radiating fin group form a multilayer structure by the secondheat-radiating fin group facing the first heat-radiating fin groupacross the first heat pipe and the second heat-radiating fin groupfacing the third heat-radiating fin group across the second heat pipe,and wherein the another end of the first heat pipe is positioned abovethe another end of the second heat pipe.

In the present specification, “above” means the installation side of thefirst heat-generating element in the direction orthogonal to theinstallation plane of the first heat-generating element.

In another aspect, the present disclosure provides a cooling device,including: a first heat pipe having one end thermally connected to afirst heat-generating element and another end thermally connected to afirst heat-radiating fin group that has a plurality of firstheat-radiating fins and a second heat-radiating fin group that has aplurality of second heat-radiating fins; and a second heat pipe havingone end thermally connected to a second heat-generating element that isdisposed closer to the second heat-radiating fin group than the firstheat-generating element and another end thermally connected to thesecond heat-radiating fin group, wherein the first heat-radiating fingroup and the second heat-radiating fin group form a multilayerstructure by the second heat-radiating fin group facing the firstheat-radiating fin group across the first heat pipe, and wherein theanother end of the first heat pipe is positioned above the another endof the second heat pipe.

In the above-mentioned aspect, the third heat-radiating fin group maynot be provided.

In another aspect, the present disclosure provides a cooling device,including: a first heat pipe having one end thermally connected to afirst heat-generating element and another end thermally connected to asecond heat-radiating fin group that has a plurality of secondheat-radiating fins; and a second heat pipe having one end thermallyconnected to a second heat-generating element that is disposed closer tothe second heat-radiating fin group than the first heat-generatingelement and another end thermally connected to the second heat-radiatingfin group and a third heat-radiating fin group that has a plurality ofthird heat-radiating fins, wherein the second heat-radiating fin groupand the third heat-radiating fin group form a multilayer structure bythe second heat-radiating fin group facing the third heat-radiating fingroup across the second heat pipe, and wherein the another end of thefirst heat pipe is positioned above the another end of the second heatpipe.

In the above-mentioned aspect, the first heat-radiating fin group maynot be provided.

Here, the first heat pipe may be introduced from a direction angled withrespect a direction in which the plurality of first heat-radiating finsare arranged.

Here, the first heat pipe may be introduced from a direction angled withrespect a direction in which the plurality of second heat-radiating finsare arranged.

Here, the second heat pipe may be introduced from a direction angledwith respect a direction in which the plurality of third heat-radiatingfins are arranged.

Here, the second heat pipe may be introduced from a direction angledwith respect a direction in which the plurality of second heat-radiatingfins are arranged.

In at least one of the above-mentioned aspects, the first heat pipe maybe provided in a plurality in parallel to one another.

In at least one of the above-mentioned aspects, the second heat pipe maybe provided in a plurality in parallel to one another.

In at least one of the above-mentioned aspects, at least one of thefirst heat pipes of the first heat pipe group may be arranged in apositional relationship that overlaps at least one of the second heatpipes of the second heat pipe group in a plan view.

In at least one of the above-mentioned aspects, none of the first heatpipes forming the first heat pipe group may overlaps any of the secondheat pipes forming the second heat pipe group in a plan view. In thepresent specification, “a plan view” means an aspect viewed from adirection above a direction parallel to the layering direction of theheat-radiating fin group.

In at least one of the above-mentioned aspects, a section of the firstheat pipe thermally connected to the second heat-radiating fin group mayhave a bend formed therein.

In at least one of the above-mentioned aspects, a section of the secondheat pipe thermally connected to the second heat-radiating fin group mayhave a bend formed therein.

In at least one of the above-mentioned aspects, portions of the firstheat pipe group thermally connected to the second heat-radiating fingroup may be arranged with left-right symmetry.

In at least one of the above-mentioned aspects, portions of the secondheat pipe group thermally connected to the second heat-radiating fingroup may be arranged with left-right symmetry.

In at least one of the above-mentioned aspects, a portion of the firstheat pipe thermally connected to the second heat-radiating fin groupand/or a portion of the second heat pipe thermally connected to thesecond heat-radiating fin group may be flattened.

In at least one of the above-mentioned aspects, the cooling device maybe used in cooling a calculation element.

According to at least some of the aspects of the present invention, thefirst heat pipes thermally connected to the first heat-generatingelement and the second heat pipes thermally connected to the secondheat-generating element are all thermally connected to the secondheat-radiating fin group; thus, even if the amount of heat generated bythe first heat-generating element differs from the amount of heatgenerated by the second heat-generating element, the secondheat-radiating fin group can make the cooling of the firstheat-generating element and the second heat-generating element uniform.Even if the difference between the amount of heat generated by the firstheat-generating element and the amount of heat generated by the secondheat-generating element causes the thermal load of the firstheat-radiating fin group to differ from the thermal load of the thirdheat-radiating fin group, the second heat-radiating fin group receivesheat from the heat pipes thermally connected to whichever of the firstheat-radiating fin group or third-heat radiating fin group that has agreater thermal load, thereby allowing for uniform cooling of thethermal load across the first heat-radiating fin group and the thirdheat-radiating fin group. Accordingly, the second heat-radiating fingroup can discharge a greater quantity of heat from the heat pipesthermally connected to the heat-radiating fin group that has the greaterthermal load. Furthermore, one aspect of the present invention makes itpossible for the heat from the heat pipes thermally connected to theheat-radiating fin group that has the greater thermal load to bedischarged in a greater quantity by the second heat-radiating fin group,thus allowing the cooling of the plurality of heat-generating elementsto be uniform as a result, and therefore making it possible to increasethe long-term reliability of the heat-generating elements.

According to at least some of the aspects of the present invention,adjusting the area ratio of the first heat-radiating fins, secondheat-radiating fins, and third heat-radiating fins makes it possible tocool the first heat-generating element and second heat-generatingelement more uniformly. In addition, in one aspect of the presentinvention, even if there is a deviation between the positions of thefirst heat-generating element and the second heat-generating element,the bending of the first heat pipes and second heat pipes makes itpossible to maintain favorable thermal connectivity between theheat-generating elements and the heat pipes and to prevent a reductionin heat-dissipating efficiency.

According to at least some of the aspects of the present invention, whenthe heat pipes are introduced in a direction angled with respect to thedirection in which the heat-radiating fins are arranged, cooling airthat has been transmitted in a direction parallel or generally parallelto the surface of the heat-radiating fins can cool not only the otherend of the heat pipes thermally connected to the heat-radiating fingroup, but also the center section of the heat pipes.

According to at least some of the aspects of the present invention,forming the first heat pipe group and/or the second heat pipe groupmakes it possible to reliably perform cooling even if the amount of heatgenerated by the first heat-generating element and/or secondheat-generating element increases. Moreover, adjusting the number of thefirst heat pipes constituting the first heat pipe group and the numberof the second heat pipes constituting the second heat pipe group canmake the cooling of both heat-generating elements uniform even if theamount of heat generated by the first heat-generating element differsfrom the second heat-generating element.

According to at least some of the aspects of the present invention, whenthe first heat pipes overlap the second heat pipes in a plan view savesspace in the cooling device, the arrangement space for the center areaof the heat pipes can be saved, and the cooling air transmitted in thedirection parallel or generally parallel to the surface of theheat-radiating fins can cool the center of the heat pipes.

According to at least some of the aspects, having a bend in the sectionof the heat pipes thermally connecting to the heat-radiating fins makesit possible to reduce the dimensions of the heat pipes in the long-axisdirection while thermally connecting the heat pipes to the respectiveplurality of heat-radiating fins that constitute the heat-radiating fingroups.

According to at least some of the aspects, when the portions of the heatpipe groups thermally connected to the heat-radiating fins are arrangedwith left-right symmetry, it is possible for the respectiveheat-radiating fins constituting the heat-radiating fin groups to morereliably contribute to the cooling of the heat-generating elements.

According to at least some of the aspects, when the portions of the heatpipes thermally connected to the heat-radiating fin groups areflattened, it is possible to further increase the contact area of theheat pipes with respect to the heat-radiating fins and to furtherimprove cooling efficiency. Furthermore, the flattening can furtherreduce pressure loss of cooling air within the heat-radiating fingroups.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory, andare intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cooling device according to Embodiment1 of the present invention.

FIG. 2 is a plan view of the cooling device according to Embodiment 1 ofthe present invention.

FIG. 3 is a bottom view of the cooling device according to Embodiment 1of the present invention.

FIG. 4 is a side view of the cooling device according to Embodiment 1 ofthe present invention.

FIG. 5 is a front view of the cooling device according to Embodiment 1of the present invention.

FIG. 6 is a rear view of the cooling device according to Embodiment 1 ofthe present invention.

FIG. 7 is a perspective view of a cooling device according to Embodiment2 of the present invention.

FIG. 8 is a perspective view of a cooling device according to Embodiment3 of the present invention.

FIG. 9 is a bottom view of the cooling device according to Embodiment 3of the present invention.

FIG. 10 is a perspective view of a cooling device according toEmbodiment 4 of the present invention.

FIG. 11 is a bottom view of the cooling device according to Embodiment 4of the present invention.

FIG. 12 is a perspective view of a cooling device according toEmbodiment 5 of the present invention.

FIG. 13 is a bottom view of the cooling device according to Embodiment 5of the present invention.

FIG. 14 is a perspective view of a cooling device according toEmbodiment 6 of the present invention.

FIG. 15 is a rear view of the cooling device according to Embodiment 6of the present invention.

FIG. 16 illustrates a cooling device used in a working example.

FIG. 17 illustrates a conventional cooling device used in a comparativeexample.

FIG. 18 is a table showing evaluation results of the working example andcomparative example.

DETAILED DESCRIPTION OF EMBODIMENTS

A cooling device according to Embodiment 1 of the present invention willbe explained below with reference to the drawings. As shown in FIG. 1,the cooling device 1 of Embodiment 1 includes first heat pipes 11thermally connected to a first heat-generating element (not shown), andsecond heat pipes 13 thermally connected to a second heat-generatingelement (not shown). The first heat pipes 11 and second heat pipes 13are all thermally connected to a common heat sink 20 of the coolingdevice 1. The heat sink 20 includes a first heat-radiating fin group 22,a second heat-radiating fin group 24, and a third heat-radiating fingroup 26.

In FIG. 1, of the first heat-radiating fin group 22, secondheat-radiating fin group 24, and third heat-radiating fin group 26, thefirst heat-radiating fin group 22 is positioned the furthest above theinstallation plane of the heat-generating elements, and the thirdheat-radiating fin group 26 is positioned the closest to theinstallation plane of the heat-generating elements.

The first heat pipes 11 receive the heat emitted from the firstheat-generating element at one end and transfer the heat toward thefirst heat-radiating fin group 22 and second heat-radiating fin group 24that are part of the heat sink 20 of the cooling device 1 and that arethermally connected to the other end of the first heat pipes 11. Theheat that has been transferred from the first heat-generating element tothe first heat-radiating fin group 22 and second heat-radiating fingroup 24 via the first heat pipes 11 is emitted to outside from thefirst heat-radiating fin group 22 and the second heat-radiating fingroup 24. The second heat pipes 13 receive the heat emitted from thesecond heat-generating element at one end and transfer the heat towardthe second heat-radiating fin group 24 and third heat-radiating fingroup 26 that are part of the heat sink 20 of the cooling device 1 andthat are thermally connected to the other end of the second heat pipes13. The heat that has been transferred from the second heat-generatingelement to the second heat-radiating fin group 24 and thirdheat-radiating fin group 26 via the second heat pipes 13 is emitted tooutside from the second heat-radiating fin group 24 and the thirdheat-radiating fin group 26.

As shown in FIGS. 1, 2, and 3, the first heat pipes 11 are arranged in aplurality (four in the drawings) in parallel in a direction that isorthogonal to the long-axis direction of the first heat pipes, therebyforming a first heat pipe group 12. The plurality of first heat pipes 11all face other adjacent first heat pipes 11 at the sides thereof.Furthermore, the plurality of first heat pipes 11 all have one endthermally connected to the first heat-generating element (not shown),thus thermally connecting one end of the first heat pipe group 12 to thefirst heat-generating element. In the cooling device 1, the one end ofthe first heat pipe group 12 directly or indirectly contacting thesurface of the first heat-generating element via a first cover 31 causesthe one end of the first heat pipe group 12 to be thermally connected tothe first heat-generating element.

As shown in FIGS. 1, 2, and 3, the second heat pipes 13 are arranged ina plurality (four in the drawings) in parallel in a direction that isorthogonal to the long-axis direction of the second heat pipes, therebyforming a second heat pipe group 14. The plurality of second heat pipes13 all face other adjacent second heat pipes 13 at the sides thereof.Furthermore, the plurality of second heat pipes 13 all have one endthermally connected to the second heat-generating element (not shown),thus thermally connecting one end of the second heat pipe group 14 tothe second heat-generating element. In the cooling device 1, the one endof the second heat pipe group 14 directly or indirectly contacting thesurface of the second heat-generating element via a second cover 32causes the one end of the second heat pipe group 14 to be thermallyconnected to the second heat-generating element.

Moreover, as shown in FIG. 6, in the cooling device 1, one end of thefirst heat pipes 11, which are round containers of a tubular material,has the side facing the first heat-generating element deformed into aplanar shape, thus assuming a reversed “U”-shape in a rear view.Furthermore, one end of the second heat pipes 13, which are roundcontainers of a tubular material, has the side facing the secondheat-generating element deformed into a planar shape, thus assuming areversed “U”-shape in a rear view. It should be noted that, in order toimprove thermal connectivity, a heat-receiving plate may be disposedbetween the heat pipe group and the heat-generating element toindirectly connect the heat pipe group to the heat-generating element,and in the cooling device 1, a heat-receiving plate 33 is disposedbetween the rear view reversed “U”-shape planar portion of the firstheat pipes 11 and the first heat-generating element, and aheat-receiving plate 34 is disposed between the rear view reversed“U”-shaped planar portion of the second heat pipes 13 and the secondheat-generating element. The method of fixing the cover that connectsthe heat pipe group to the heat-generating element has no particularlimitations, and can be a screw or the like, for example.

As shown in FIGS. 1, 2, and 3, in the cooling device 1, the first cover31 to which the first heat pipe group 12 is thermally connected and thesecond cover 32 to which the second heat pipe group 14 is thermallyconnected are arranged on the same straight line (on the same plane) inorder to correspond to the first heat-generating element and the secondheat-generating element being arranged on the same straight line (on thesame plane). In the cooling device 1, the straight line connecting thefirst cover 31 and the second cover 32 intersects the lengthwisedirection of the heat sink 20, which has a generally cuboid externalshape. Moreover, the straight line connecting the first cover 31 and thesecond cover 32 intersects the center of the lengthwise direction of theheat sink 20. In the cooling device 1, the second cover 32 is disposedcloser to the heat sink 20 than the first cover 31.

As described above, the other end of the first heat pipes 11 isthermally connected to the first heat-radiating fin group 22 and thesecond heat-radiating fin group 24, thereby thermally connecting theother end of the first heat pipe group 12 to the first heat-radiatingfin group 22 and the second heat-radiating fin group 24. Furthermore,the other end of the second heat pipes 13 is thermally connected to thesecond heat-radiating fin group 24 and the third heat-radiating fingroup 26, thereby thermally connecting the other end of the second heatpipe group 14 to the second heat-radiating fin group 24 and the thirdheat-radiating fin group 26. In addition, the portion (center area)between the one end and the other end of both the first heat pipe group12 and the second heat pipe group 14 has a linear shape in a plan view.

The second cover 32 is disposed closer to the heat sink 20 than thefirst cover 31; therefore, the first heat pipe group 12 is longer thanthe second heat pipe group 14. Moreover, the first heat pipe group 12has a stepped portion 27 for avoiding the second cover 32 and theportion between the one end and the other end of the second heat pipegroup 14. The stepped portion 27 makes it possible for the portionbetween the one end and the other end of the first heat pipe group 12 tobe positioned on top of the second cover 32 and on top of the portionbetween the one end and the other end of the second heat pipe group 14.

Accordingly, as shown in FIGS. 2 and 3, the portion between the one endand other end of the second heat pipe group 14 is in a positionalrelationship that overlaps the portion between the one end and other endof the first heat pipe group 12 in a plan view and bottom view.

Even if a deviation were to occur between the position of the firstheat-generating element and the position of the second heat-generatingelement, the portion between the one end and other end of the first heatpipe group 12 (e.g., the stepped portion 27) and the portion between theone end and other end of the second heat pipe group 14 would bend, thusmaking it possible to maintain favorable thermal connectivity betweenthe heat-generating elements and the first heat pipe group 12 and secondheat pipe group 14, and making it possible to prevent a reduction inheat-dissipating efficiency. The portion between the one end and otherend of the second heat pipe group 14 is in a positional relationshipthat overlaps the portion between the one end and other end of the firstheat pipe group 12 in a plan view and bottom view, which also makes itpossible to save space with respect to the arrangement area for the heatpipes.

As shown in FIG. 1, the heat sink 20 having a generally cuboid externalshape includes the first heat-radiating fin group 22 having a generallycuboid external shape, the second heat-radiating fin group 24 having agenerally cuboid external shape adjacent to the first heat-radiating fingroup 22, and the third heat-radiating fin group 26 having a generallycuboid external shape adjacent to the second heat-radiating fin group24. Moreover, the first heat-radiating fin group 22, secondheat-radiating fin group 24, and third heat-radiating fin group 26 arelayered on top of one another. In other words, in the cooling device ofthe present invention, the heat sink has a multilayer structure due tohaving a plurality of heat-radiating fin groups, and the heat sink 20 ofthe cooling device 1 has three heat-radiating fin groups, and is thus athree-layer multilayer structure.

The first heat-radiating fin group 22 includes a first support member 41and a plurality of first heat-radiating fins 21. The firstheat-radiating fins 21 attaching to the first support member 41thermally connects the first heat-radiating fins 21 to the first supportmember 41. Furthermore, the first heat-radiating fins 21 are eacharrayed in a direction parallel to the lengthwise direction of the heatsink 20. In addition, the first heat-radiating fins 21 are attached tothe first support member 41 such that the surfaces of the firstheat-radiating fins are parallel to the plan view linearly shapedportions between the one end and other end of the first heat pipe group12 and second heat pipe group 14. Accordingly, the surfaces of the firstheat-radiating fins 21 form the widthwise direction of the heat sink 20and first heat-radiating fin group 22.

The second heat-radiating fin group 24 includes a second support member42 and a plurality of second heat-radiating fins 23. The secondheat-radiating fins 23 attaching to the second support member 42thermally connects the second heat-radiating fins 23 to the secondsupport member 42. Furthermore, the second heat-radiating fins 23 areeach arrayed in a direction parallel to the lengthwise direction of theheat sink 20. In addition, the second heat-radiating fins 23 areattached to the second support member 42 such that the surfaces of thesecond heat-radiating fins are parallel to the plan view linearly shapedportions between the one end and other end of the first heat pipe group12 and second heat pipe group 14. Accordingly, the surfaces of thesecond heat-radiating fins 23 form the widthwise direction of the heatsink 20 and second heat-radiating fin group 24.

The other end of the first heat pipe group 12 is disposed between thefirst heat-radiating fin group 22 and second heat-radiating fin group24. The other end of the first heat pipe group 12 directly or indirectlycontacting the first heat-radiating fin group 22 and secondheat-radiating fin group 24 thermally connects the first heat pipe group12 to the first heat-radiating fin group 22 and second heat-radiatingfin group 24. In other words, the heat sink 20 has the firstheat-radiating fin group 22 and second heat-radiating fin group 24formed on the boundary of the other end of the first heat pipe group 12,and the second heat-radiating fin group 24 faces the firstheat-radiating fin group 22 across the first heat pipe group 12. Inaddition, in the cooling device 1, the top of the second heat-radiatingfins 23 contacts the first support member 41, and thus the firstheat-radiating fins 21 and second heat-radiating fins 23 are thermallyconnected via the first support member 41.

Furthermore, the first heat-radiating fin group 22 has a first opening51 between the first heat-radiating fins 21 and other adjacent firstheat-radiating fins 21, and the first heat pipe group 12 is introducedinto the heat sink 20, or namely, the space between the firstheat-radiating fin group 22 and second heat-radiating fin group 24, in adirection that is angled (here in this example, a perpendiculardirection, that is parallel to the surface of the fins 21) with respectto a direction along which the plurality of first heat-radiating fins 21are arranged. In a similar manner, the second heat-radiating fin group24 has a second opening 52 between the second heat-radiating fins 23 andother adjacent second heat-radiating fins 23, and the first heat pipegroup 12 is introduced into the heat sink 20, or namely, the spacebetween the first heat-radiating fin group 22 and second heat-radiatingfin group 24, in a direction that is angled (here in this example, aperpendicular direction, that is parallel to the surface of the fins 23)with respect to a direction along which the plurality of secondheat-radiating fins 23 are arranged.

The surface of the first heat-radiating fins 21 and the surface of thesecond heat-radiating fins 23 are disposed in a direction parallel tothe plan view linearly shaped portions between the one end and other endof the first heat pipe group 12 and second heat pipe group 14; thus,both the first opening 51 and second opening 52 open in a directionparallel to the portions between the one end and other end of the firstheat pipe group 12 and second heat pipe group 14.

Accordingly, in the cooling device 1, the first heat pipe group 12 isintroduced into the heat sink 20 from the direction parallel to thefirst opening 51 and second opening 52, or namely, from the directionorthogonal to the lengthwise direction of the heat sink 20.

The third heat-radiating fin group 26 includes a third support member 43and a plurality of third heat-radiating fins 25. In this example, thesecond support member 42 and third support member 43 are the same singlemember; i.e., the third support member 43 is identical to the secondsupport member 42. The third heat-radiating fins 25 attaching to thethird support member 43 thermally connects the third heat-radiating fins25 to the third support member 43. Furthermore, the third heat-radiatingfins 25 are each arrayed in a direction parallel to the lengthwisedirection of the heat sink 20. In addition, the third heat-radiatingfins 25 are attached to the third support member 43 such that thesurfaces of the third heat-radiating fins are parallel to the plan viewlinearly shaped portions between the one end and other end of the firstheat pipe group 12 and second heat pipe group 14. Accordingly, thesurfaces of the third heat-radiating fins 25 form the widthwisedirection of the heat sink 20 and third heat-radiating fin group 26.

The other end of the second heat pipe group 14 is disposed between thesecond heat-radiating fin group 24 and third heat-radiating fin group26. The other end of the second heat pipe group 14 directly orindirectly contacting the second heat-radiating fin group 24 and thirdheat-radiating fin group 26 thermally connects the second heat pipegroup 14 to the second heat-radiating fin group 24 and thirdheat-radiating fin group 26. In other words, the heat sink 20 has thesecond heat-radiating fin group 24 and third heat-radiating fin group 26formed on the boundary of the other end of the second heat pipe group14, and the second heat-radiating fin group 24 faces the thirdheat-radiating fin group 26 across the second heat pipe group 14. Inaddition, in the cooling device 1, the top of the third heat-radiatingfins 25 contacts the second support member 42, and thus the secondheat-radiating fins 23 and third heat-radiating fins 25 are thermallyconnected via the second support member 42.

Accordingly, the second heat-radiating fin group 24 is positionedbetween the second heat pipe group 14 and the first heat pipe group 12.

Furthermore, the third heat-radiating fin group 26 has a third opening53 between the third heat-radiating fins 25 and other adjacent thirdheat-radiating fins 25, and the second heat pipe group 14 is introducedinto the heat sink 20, or namely, the space between the secondheat-radiating fin group 24 and third heat-radiating fin group 26, in adirection that is angled (here in this example, a perpendiculardirection, that is parallel to the surface of the fins 25) with respectto a direction along which the plurality of third heat-radiating fins 25are arranged.

The surface of the third heat-radiating fins 25 are disposed in adirection parallel to the plan view linearly shaped portions between theone end and other end of the first heat pipe group 12 and second heatpipe group 14; thus, the third opening 53 also opens in a directionparallel to the portions between the one end and other end of the firstheat pipe group 12 and second heat pipe group 14.

Accordingly, in the cooling device 1, the second heat pipe group 14 isintroduced into the heat sink 20 from the direction parallel to thesecond opening 52 and third opening 53, or namely, from the directionorthogonal to the lengthwise direction of the heat sink 20.

As shown in FIG. 1, in the cooling device 1, the first heat-radiatingfin group 22 is positioned furthest above the installation plane of theheat-generating element, and the third heat-radiating fin group 26 ispositioned closest to the installation plane of the heat-generatingelement; therefore, the other end of the first heat pipe group 12 isintroduced into the heat sink 20 above the other end of the second heatpipe group 14.

As shown in FIG. 2, in the cooling device 1, the four first heat pipes11 constituting the first heat pipe group 12 have a bend at the portionthat is thermally connected to the first heat-radiating fin group 22 andsecond heat-radiating fin group 24—i.e., the portions sandwiched betweenthe first heat-radiating fin group 22 and the second heat-radiating fingroup 24. Accordingly, the first heat pipes 11 all have a generally“L”-shape in a plan view in these portions. Furthermore, the two firstheat pipes 11 on the right side are bent to the right direction, whereasthe two first heat pipes 11 on the left side are bent to the leftdirection. In other words, the first heat pipes 11 on the left side andthe first heat pipes 11 on the right side have bends with bendingdirections that are opposite of each other.

Thus, as shown in FIGS. 2 and 4, the four first heat pipes 11 all havethe other ends thereof extending in the direction parallel to thelengthwise direction of the heat sink 20 due to the bends. In thecooling device 1, the other ends of the first heat pipes 11 extending inthe direction parallel to the lengthwise direction of the heat sink 20all reach the ends of the heat sink 20 in the lengthwise direction.

Furthermore, as shown in FIG. 2, the radius of curvature of the bends ofthe first heat pipes 11 positioned on both ends of the first heat pipegroup 12 is less than the radius of curvature of the bends of theadjacent first heat pipes 11, and the first heat pipes 11 positionedcloser inside the first heat pipe group 12 have a correspondinglygreater radius of curvature of the bends thereof. Moreover, the otherend of the first heat pipe group 12 thermally connected to the firstheat-radiating fin group 22 and second heat-radiating fin group 24 isarranged so as to have left-right symmetry about the centerline in thelengthwise direction of the heat sink 20 in a plan view. Accordingly,the heat-radiating fins constituting the first heat-radiating fin group22 and second heat-radiating fin group 24 reliably contribute to coolingof the heat-generating element, and thus heat can be efficientlydissipated at the entirety of the first heat-radiating fin group 22 andsecond heat-radiating fin group 24.

As shown in FIG. 3, in the cooling device 1, the four second heat pipes13 constituting the second heat pipe group 14 have a bend at the portionthat is thermally connected to the second heat-radiating fin group 24and third heat-radiating fin group 26. Accordingly, the second heatpipes 13 all have a generally “L”-shape in a plan view. Furthermore, thetwo second heat pipes 13 on the right side are bent to the rightdirection, whereas the two second heat pipes 13 on the left side arebent to the left direction. In other words, the second heat pipes 13 onthe left side and the second heat pipes 13 on the right side have bendswith bending directions that are opposite of each other.

Thus, as shown in FIGS. 3 and 4, the four second heat pipes 13 all havethe other ends thereof extending in the direction parallel to thelengthwise direction of the heat sink 20 due to the bends. In thecooling device 1, the other ends of the second heat pipes 13 extendingin the direction parallel to the lengthwise direction of the heat sink20 all reach the ends of the heat sink 20 in the lengthwise direction.

Furthermore, as shown in FIG. 3, the radius of curvature of the bends ofthe second heat pipes 13 positioned on both ends of the second heat pipegroup 14 is less than the radius of curvature of the bends of theadjacent second heat pipes 13, and the second heat pipes 13 positionedcloser inside the second heat pipe group 14 have a correspondinglygreater radius of curvature of the bends thereof. Moreover, the otherend of the second heat pipe group 14 thermally connected to the secondheat-radiating fin group 24 and third heat-radiating fin group 26 isarranged so as to have left-right symmetry about the centerline in thelengthwise direction of the heat sink 20 in a bottom view. Accordingly,the heat-radiating fins constituting the second heat-radiating fin group24 and third heat-radiating fin group 26 reliably contribute to coolingof the heat-generating element, and thus heat can be efficientlydissipated at the entirety of the second heat-radiating fin group 24 andthird heat-radiating fin group 26.

As shown in FIG. 1, in the cooling device 1, the side of the firstheat-radiating fins 21 facing the second heat-radiating fin group 24 hasa cutout part 29 corresponding to the size and shape of the other end ofthe first heat pipe group 12, and the other end of the first heat pipegroup 12 is introduced into the heat sink 20 via the cutout part 29.Furthermore, the side of the third heat-radiating fins 25 facing thesecond heat-radiating fin group 24 has a cutout part 29 corresponding tothe size and shape of the other end of the second heat pipe group 14,and the other end of the second heat pipe group 14 is introduced intothe heat sink 20 via the cutout part 29.

In the cooling device 1, the first heat pipes 11 and second heat pipes13 are round containers of a tubular material, and as shown in FIG. 4,the other end of the first heat pipes 11 thermally connected to the heatsink 20 and the other end of the second heat pipes 13 thermallyconnected to the heat sink 20 are flattened. The flattening increasesthe contact area of the first heat pipes 11 and second heat pipes 13with respect to the heat sink 20, which makes it possible to improvecooling efficiency. Furthermore, the flattening can reduce pressure lossof cooling air within the heat sink 20.

In the cooling device 1, the first heat pipes 11 constituting the firstheat pipe group 12 all have the same diameter, and the second heat pipes13 constituting the second heat pipe group 14 all have the samediameter. Moreover, the diameters of the first heat pipes 11 and thediameters of the second heat pipes 13 are all the same.

The material of the first heat-radiating fins 21, second heat-radiatingfins 23, and third heat-radiating fins 25 has no particular limitations,and examples include a metal such as copper, copper alloy, aluminum,aluminum alloy, or the like. In the cooling device 1, the heat sink 20has excellent heat-dissipating efficiency; thus, by using aluminum,which has inferior thermal conductivity compared to copper but islight-weight, it is possible to maintain the favorable heat-dissipatingefficiency of the cooling device while making the cooling devicelight-weight. In addition, the material of the first support member 41,second support member 42, third support member 43, first cover 31, andsecond cover 32 has no particular limitations, and examples include ametal such as copper, copper alloy, aluminum, aluminum alloy, or thelike.

Furthermore, the material of the container of the first heat pipes 11and second heat pipes 13 has no particular limitations, and examplesinclude a metal such as copper, copper alloy, aluminum, aluminum alloy,stainless steel, and the like. Moreover, the working fluid sealed in thefirst heat pipes 11 and second heat pipes 13 can be water, achlorofluorocarbon alternative, perfluorocarbon, cyclopentane, or thelike.

As described above, in the cooling device 1, the first heat pipe group12 thermally connected to the first heat-generating element and thesecond heat pipe group 14 thermally connected to the secondheat-generating element are both thermally connected to the secondheat-radiating fin group 24. Accordingly, even if the difference betweenthe amount of heat generated by the first heat-generating element andthe amount of heat generated by the second heat-generating elementcauses the amount of heat received by the first heat-radiating fin group22 to differ from the amount of heat received by the thirdheat-radiating fin group 26, the second heat-radiating fin group 24 canreceive heat from whichever heat pipe group thermally connected to theheat-radiating fin group has received a relatively greater heat loadamong the first heat-radiating fin group 22 and third heat-radiating fingroup 26; thus, it is possible to make the thermal load of the firstheat-radiating fin group 22 and third heat-radiating fin group 26uniform, which makes it possible to have uniform cooling of the firstheat-generating element and the second heat-generating element.

In addition, by introducing the first heat pipe group 12 and second heatpipe group 14 into the heat sink 20 in a direction parallel or generallyparallel to the surface of the first heat-radiating fins 21, secondheat-radiating fins 23, and third heat-radiating fins 25, a cooling wind(from a fan, for example) supplied in such a direction can cool not onlythe heat sink 20 and the other ends of the first heat pipe group 12 andsecond heat pipe group 14 thermally connected to the heat sink 20, butalso the portions between the one ends and other ends of the first heatpipe group 12 and second heat pipe group 14.

Furthermore, in the embodiment of the cooling device 1, the area ratioof the first heat-radiating fins 21, second heat-radiating fins 23, andthird heat-radiating fins 25 may preferably be approximately 1:1.5:1,but the area ratio can be selected as appropriate in accordance with thedifference in heat generated between the first heat-generating elementand the second heat-generating element, and appropriately adjusting thearea ratio can make it possible to further make the cooling of the firstheat-generating element and second heat-generating element uniform.

Next, a cooling device according to Embodiment 2 of the presentinvention will be described with reference to the drawings. Componentsthat are the same as those in the cooling device 1 of Embodiment 1 areassigned the same reference characters.

As shown in FIG. 7, the cooling device 2 of Embodiment 2 has apositional relationship configured such that portions between one endand another end of a second heat pipe group 114 that has a plurality(six in the drawing) of second heat pipes 113 do not overlap in a planview portions between one end and another end of a first heat pipe group12 that has a plurality of first heat pipes 11 (six in the drawing). Inother words, the first heat-generating element and secondheat-generating element are on the same plane, but are not on the samestraight line intersecting with the lengthwise direction of the heatsink 20, which has a generally cuboid external shape. Based on this, inthe cooling device 1, a first cover 31 thermally connected to the firstheat pipe group 12 and a second cover 132 thermally connected to thesecond heat pipe group 114 are not placed on the same straight linementioned above.

In the cooling device 2, in a similar manner to the cooling device 1,the first heat pipe group 12 is introduced into the heat sink 20, ornamely, into a space between the first heat-radiating fin group 22 andsecond heat-radiating fin group 24, from the center of the lengthwisedirection of the heat sink 20. Meanwhile, the second heat pipe group 114is introduced into the heat sink 20, or namely, into a space between thesecond heat-radiating fin group 24 and third heat-radiating fin group 26not from the center in the lengthwise direction of the heat sink 20, butrather from the vicinity of an end of the heat sink.

Accordingly, while not shown in the drawing, the first heat pipe group12 has the first heat pipes 11 arranged with left-right symmetry in aplan view inside the heat sink 20, in a similar manner to the coolingdevice 1. However, the second heat pipe group 114 is introduced into theheat sink 20 from the vicinity of an end of the heat sink 20 in alengthwise direction; therefore, the second heat pipes 113 have a bendat the portion thermally connected to the heat sink 20, but are notarranged with left-right symmetry in a plan view inside the heat sink20. Moreover, in the cooling device 2, the first heat pipes 11 andsecond heat pipes 113, which are round containers of a tubular material,are not deformed on the end (i.e., the one end) thermally connected tothe heat-generating element.

Similar to the cooling device 1 of Embodiment 1, in the cooling device 2of Embodiment 2, even if the difference between the amount of heatgenerated by the first heat-generating element and the amount of heatgenerated by the second heat-generating element causes the amount ofheat received by the first heat-radiating fin group 22 to differ fromthe amount of heat received by the third heat-radiating fin group 26,the second heat-radiating fin group 24 can receive heat from whicheverheat pipe group thermally connected to the heat-radiating fin group hasreceived a relatively greater thermal load among the firstheat-radiating fin group 22 and third heat-radiating fin group 26; thus,it is possible to make the thermal load of the first heat-radiating fingroup 22 and third heat-radiating fin group 26 uniform, which makes itpossible to have uniform cooling of the first heat-generating elementand the second heat-generating element.

Next, a cooling device according to Embodiment 3 of the presentinvention will be described with reference to the drawings. Componentsthat are the same as those in the cooling device 1 of Embodiment 1 areassigned the same reference characters.

In the cooling device 1 of Embodiment 1, both the first heat pipe group12 and second heat pipe group 14 were introduced into the heat sink 20from the center of the heat sink 20 in the lengthwise direction, but asshown in FIGS. 8 and 9, in a cooling device 3 of Embodiment 3, both afirst heat pipe group 212 and a second heat pipe group 214 areintroduced into the heat sink 20 not from the center of the heat sink 20in the lengthwise direction, but rather from the vicinity of an end ofthe heat sink. In the cooling device 3, both the first heat pipe group212 and the second heat pipe group 214 are introduced into the heat sink20 from the same vicinity of the end of the heat sink. In the coolingdevice 3, the first heat pipe group 212 is constituted by six first heatpipes 211, and the second heat pipe group 214 is constituted by sixsecond heat pipes 213.

Both the first heat pipe group 212 and second heat pipe group 214 areintroduced into the heat sink 20 from the vicinity of the end of theheat sink 20 in the lengthwise direction; thus, the first heat pipes 211and second heat pipes 213 all have a bend at the portion that isthermally connected to the heat sink 20, but the first and second heatpipes are not arranged with left-right symmetry in a plan view insidethe heat sink 20.

In addition, in the cooling device 3, the first heat pipes 211 andsecond heat pipes 213, which are round containers of a tubular material,are not deformed on the end (i.e., the one end) thermally connected tothe heat-generating element. In a similar manner to the cooling device 2of Embodiment 2, the cooling device 3 also makes it possible to make thecooling of the first heat-generating element and second heat-generatingelement uniform.

Next, a cooling device according to Embodiment 4 of the presentinvention will be described with reference to the drawings. Componentsthat are the same as those in the cooling device 1 of Embodiment 1 areassigned the same reference characters.

As shown in FIGS. 10 and 11, the cooling device 4 of Embodiment 4 has apositional relationship configured such that portions between one endand another end of a first heat pipe group 312 that has first heat pipes311 do not overlap in a plan view portions between one end and anotherend of a second heat pipe group 14 that has second heat pipes 13. Inother words, similar to the cooling device 1 of Embodiment 1, the secondheat pipe group 13 is introduced into the heat sink 20 from the centerof the heat sink 20 in the lengthwise direction, whereas the first heatpipe group 312 is introduced into the heat sink 20 from the vicinity ofthe end of the heat sink, rather than from the center of the heat sink20 in the lengthwise direction. In the cooling device 4, the first heatpipe group 312 is constituted by six first heat pipes 311, and thesecond heat pipe group 14 is constituted by six second heat pipes 13.

Accordingly, in a similar manner to the cooling device 1 of Embodiment1, the second heat pipe group 14 has the second heat pipes 13 arrangedwith left-right symmetry in a plan view inside the heat sink 20.However, the first heat pipe group 312 is introduced into the heat sink20 from the vicinity of the end of the heat sink 20 in a lengthwisedirection; therefore, the first heat pipes 311 have a bend at theportion thermally connected to the heat sink 20, but are not arrangedwith left-right symmetry in a plan view inside the heat sink 20. In thecooling device 4, the bends in the two first heat pipes 311 on the endside in the lengthwise direction of the heat sink 20 bend toward the endof the heat sink 20 in the lengthwise direction, and the bends in thefour first heat pipes 311 on the center side of the heat sink 20 bendtoward the center of the heat sink 20.

In addition, in the cooling device 4, the first heat pipes 311 andsecond heat pipes 13, which are round containers of a tubular material,are not deformed on the end (i.e., the one end) thermally connected tothe heat-generating element. In a similar manner to the cooling device 2of Embodiment 2, the cooling device 4 makes it possible to make thecooling of the first heat-generating element and second heat-generatingelement uniform.

Next, a cooling device according to Embodiment 5 of the presentinvention will be described with reference to the drawings. Componentsthat are the same as those in the cooling device 1 of Embodiment 1 areassigned the same reference characters.

As shown in FIGS. 12 and 13, in the cooling device 5 of Embodiment 5,there are three heat-generating elements (and thus, three covers), andbased on this, three heat pipe groups, with the heat sink having afour-layer structure that has four heat-radiating fin groups. In thecooling device 5, the first heat-generating element (not shown) and thesecond heat-generating element (not shown) are arranged on the samestraight line (and on the same plane), and additionally the thirdheat-generating element (not shown) is also arranged on the samestraight line (and on the same plane) as the first heat-generatingelement and the second heat-generating element; based on this, the firstcover 31 thermally connected to the first heat pipe group 12 and thesecond cover 32 thermally connected to the second heat pipe group 14 arearranged on the same straight line (and the same plane), andadditionally the third cover 430 thermally connected to the third heatpipe group 416 is also arranged on the same straight line (and on thesame plane) as the first cover 31 and second cover 32.

In the cooling device 5, a plurality of the third heat pipes 415 (six inthe drawings; the same as the first heat pipe group 12 and second heatpipe group 14) are arranged in parallel to each other in a directionorthogonal to the long-axis direction in order to form the third heatpipe group 416. Furthermore, in the cooling device 5, the third cover430 is located at the position furthest from the heat sink 420, and thusthe third heat pipes 415 have the longest length.

As shown in FIG. 12, the heat sink 420 having a generally cuboidexternal shape includes the first heat-radiating fin group 22 having agenerally cuboid external shape, the second heat-radiating fin group 24having a generally cuboid external shape adjacent to the firstheat-radiating fin group 22, the third heat-radiating fin group 26having a generally cuboid external shape adjacent to the secondheat-radiating fin group 24, and additionally the fourth heat-radiatingfin group 28 having a generally cuboid external shape adjacent to thefirst heat-radiating fin group 22. Moreover, the first heat-radiatingfin group 22, second heat-radiating fin group 24, third heat-radiatingfin group 26, and fourth heat-radiating fin group 28 are layered on topof one another. The fourth heat-radiating fin group 28 has the samestructure as the first heat-radiating fin group 22, secondheat-radiating fin group 24, and third heat-radiating fin group 26.

In the cooling device 5, the other end of the first heat pipe group 12is disposed between the first heat-radiating fin group 22 and secondheat-radiating fin group 24; the other end of the second heat pipe group14 is disposed between the second heat-radiating fin group 24 and thirdheat-radiating fin group 26; and additionally, the other end of thethird heat pipe group 416 is disposed between the first heat-radiatingfin group 22 and fourth heat-radiating fin group 28. The heat sink 420has the first heat-radiating fin group 22 and fourth heat-radiating fingroup 28 formed about the other end of the third heat pipe group 416,and the fourth heat-radiating fin group 28 faces the firstheat-radiating fin group 22 across the third heat pipe group 416.Furthermore, the other end of the third heat pipe group 416 is arrangedwith left-right symmetry in a plan view inside the heat sink 420, in asimilar manner to the first heat pipe group 12 and second heat pipegroup 14.

Moreover, in the cooling device 5, the first heat pipes 11, second heatpipes 13, and third heat pipes 415, which are round containers of atubular material, are not deformed on the end (i.e., the one end)thermally connected to the heat-generating element.

In the cooling device 5, even if the amount of heat generated among thethree heat-generating elements differs, the second heat-radiating fingroup 24 and additionally the first heat-radiating fin group 22 canreceive heat from the heat pipe group thermally connected to theheat-radiating fin group that has received a relatively large thermalload; thus, in a similar manner to the cooling device 1 of Embodiment 1,it is possible to make the cooling of a plurality (three in FIGS. 11 and12) of heat-generating elements uniform.

Next, a cooling device according to Embodiment 6 of the presentinvention will be described with reference to the drawings. Componentsthat are the same as those in the cooling device 1 of Embodiment 1 areassigned the same reference characters.

As shown in FIGS. 14 and 15, in a cooling device 6 of Embodiment 6,within the heat sink 520 the first heat-radiating fin group 21 is notprovided on the sides of the first heat pipe group 12, and the thirdheat-radiating fins 25 are also not provided on the sides of the secondheat pipe group 14. In other words, the top of the second heat-radiatingfins 23 does not contact the first support member 41, and the firstheat-radiating fins 21 are not thermally connected to the secondheat-radiating fins 23 via the first support member 41. Furthermore, thetop of the third heat-radiating fins 25 does not contact the secondsupport member 42, and the second heat-radiating fins 23 are notthermally connected to the third heat-radiating fins 25 via the secondsupport member 42. Accordingly, in the cooling device 6, the thirdsupport member 43 to which the third heat-radiating fins 25 are attachedis not shared by the second support member 42.

In the cooling device 6, the first heat pipe group 12 is constituted bysix first heat pipes 11, and the second heat pipe group 14 isconstituted by six second heat pipes 13. In addition, the shape of theheat sink 520 of the cooling device 6 is a generally cuboid shape with alength in the lengthwise direction that is longer relative to the lengthin the widthwise direction, as compared to the cooling device 1 ofEmbodiment 1. Moreover, as shown in FIG. 15, in the cooling device 6,the first heat pipes 11 and second heat pipes 13, which are roundcontainers of a tubular material, are not deformed on the end (i.e., theone end) side thermally connected to the heat-generating element.Furthermore, in the cooling device 6, a heat-receiving plate 33 isdisposed between the first heat pipe group 12 and first heat-generatingelement (not shown), and a heat-receiving plate 34 is disposed betweenthe second heat pipe group 14 and the second heat-generating element(not shown). In the cooling device 6, the heat-receiving plate 33 hastrenches formed therein for accommodating the heat-generating elementside of the first heat pipe group 12, and the heat-receiving plate 34has trenches formed therein for accommodating the heat-generatingelement side of the second heat pipe group 14.

As in above configurations, in the cooling device 6, the first heatpipes 11 thermally connected to the first heat-generating element andthe second heat pipes 13 thermally connected to the secondheat-generating element are all thermally connected to the secondheat-radiating fin group 24; therefore, even if the amount of heatgenerated by the first heat-generating element differs from the amountof heat generated by the second heat-generating element, the secondheat-radiating fin group 24 can make the cooling of the firstheat-generating element and second heat-generating element uniform.

Next, a usage example of the cooling device of the present inventionwill be described. The use application of the cooling device of thepresent invention has no particular limitations, and can be a coolingdevice for an apparatus equipped with an electronic component having aheat-generating element such as a computer or server, or as a coolingdevice for a battery or the like, for example. The cooling device of therespective embodiments described above has bends in the first heat pipes11 and second heat pipes 13 & 113 at the section of these heat pipesthermally connected to the heat sink 20, and these bends reduce thedimensions in the long-axis direction of the first heat pipe group 12and second heat pipe groups 14 & 114 while ensuring the dimensions ofthe heat sink 20 in the lengthwise direction; thus, the cooling deviceof the respective embodiments described above is suitable for thecooling of a plurality of heat-generating elements in a server, forexample.

Next, another embodiment of the cooling device of the present inventionwill be described. In the respective embodiments above, the number ofheat pipes constituting the first heat pipe group and second heat pipegroup was four or eight, but the number of heat pipes can be selected asappropriate depending on the amount of heat generated by theheat-generating element, and the number may be a single heat pipe, twoto three heat pipes, five heat pipes, or seven or more heat pipes.Furthermore, the number of heat pipes constituting the first heat pipegroup and the number of heat pipes constituting the second heat pipegroup may be the same or different from each other.

In addition, in the respective embodiments described above, the firstheat pipe group was introduced into the heat sink from the directionorthogonal to the lengthwise direction of the heat sink, but the firstheat pipe group may be introduced into the heat sink in a direction thatis angled, but not right-angled, with respect to a direction in which aplurality of heat-radiating fins are arranged, and thus may beintroduced into the heat sink from a direction at an obtuse angle to thelengthwise direction of the heat sink. Similarly, in the respectiveembodiments described above, the second heat pipe group was introducedinto the heat sink from the direction orthogonal to the lengthwisedirection of the heat sink, but the second heat pipe group may beintroduced into the heat sink in a direction that is angled, but notright-angled, with respect to a direction in which a plurality ofheat-radiating fins are arranged, and thus may be introduced into theheat sink from a direction at an obtuse angle to the lengthwisedirection of the heat sink.

Furthermore, in the respective embodiments described above, there weretwo or three heat pipe groups based on there being two or threeheat-generating elements, and the heat sink was a three- or four-layerstructure having three or four heat-radiating fin groups, but the numberof heat pipes group has no particular limitations; there may be four ormore heat pipe groups, and based on this, the heat sink may be astructure with five or more layers having five or more heat-radiatingfin groups, for example.

Moreover, in the respective embodiments described above, the first heatpipes constituting the first heat pipe group were all the same diameter,but the first heat pipes may have differing diameters as necessary andappropriate. Similarly, the second heat pipes constituting the secondheat pipe group were all the same diameter, but the second heat pipesmay have differing diameters as necessary and appropriate. Furthermore,in the respective embodiments described above, the diameter of the firstheat pipes was the same as the diameter of the second heat pipes, butthese diameters may differ based on the amount of heat generated by thefirst heat-generating element and second heat-generating element asappropriate.

In addition, in the respective embodiments described above, when theother ends of the heat pipe groups are introduced into the heat sink 20from the center of the heat sink in the lengthwise direction, the heatpipes were arranged with left-right symmetry in a plan view inside theheat sink, but the heat pipes do not necessarily need to be arrangedwith left-right symmetry, depending on the heat-generating state of theheat-generating element. In the respective embodiments described above,the heat-radiating fins were attached to the support member, but theheat-radiating fins may be directly attached via a method such assoldering to the first heat pipes or second heat pipes without using thesupport member.

In the respective embodiments described above, the third heat-radiatingfin group, which was thermally connected to the second heat pipe group,was provided, but the third heat-radiating fin group does notnecessarily need to be provided, depending on usage conditions, such asif the thermal load of the second heat pipe group is very light. In therespective embodiments described above, the first heat-radiating fingroup, which was thermally connected to the first heat pipe group, wasprovided, but the first heat-radiating fin group does not necessarilyneed to be provided, depending on usage conditions, such as if thethermal load of the first heat pipe group is very light.

Working Examples

Next, working examples of the present invention will be explained, butthe present invention is not limited to these examples to the extentthat there is no departure from the spirit of the present invention.

The cooling device 1 of Embodiment 1 was used as the cooling device ofthe working example. The dimensions of the parts of the cooling device 1of Embodiment 1 used in the working example are shown in FIG. 16. Theunit of the dimensions is millimeters. In the cooling device 1 of theworking example, the four first heat pipes 11, which are roundcontainers of a tubular material, and the four second heat pipes 13,which are also round containers of a tubular material, are both 8 mm indiameter and have a flattened section that is 4 mm thick. The firstheat-radiating fins 21, second heat-radiating fins 23, and thirdheat-radiating fins 25 are all made of aluminum with a thickness of 0.15mm and are arrayed at a fin pitch of 1.5 mm.

A conventional cooling device 7 shown in FIG. 7 was used as acomparative example. The unit of the dimensions in FIG. 17 ismillimeters. As shown in FIG. 17, the dimensions of a first cover 731,the dimensions of a second cover 732, the dimensions in the lengthwisedirection of flat-type heat pipes 711, and the vertical and horizontaldimensions of a first heat-radiating fin group 722 and secondheat-radiating fin group 724 of the conventional cooling device 7 arethe same as the cooling device 1.

In the conventional cooling device 7, a heat-radiating fin groupcorresponding to the third heat-radiating fin group of the workingexample is not provided, but rather six flat-type heat pipes 711 arearranged between the first heat-radiating fin group 722 and secondheat-radiating fin group 724. Each of the flat-type heat pipes 711 is aflattened round tubular material that is 8 mm in diameter with athickness of 4 mm. Furthermore, the flat-type heat pipes 711 arearranged in parallel such that the flat sections face and are adjacentto one another. Of the six flat-type heat pipes 711, the three flat-typeheat pipes 711 on the right side bend in the right direction, whereasthe three flat-type heat pipes 711 on the left side bend in the leftdirection.

Moreover, the first heat-radiating fins 721 and second heat-radiatingfins 723 are all made of aluminum with a thickness of 0.15 mm and arearrayed at a fin pitch of 1.5 mm, in a similar manner to the coolingdevice 1 of the working example. In the conventional cooling device 7,the reason that the number of flat-type heat pipes 711 is restricted tosix is due to the width direction dimensions of the first cover 731 andsecond cover 732, which are heat-receiving members, being restricted to40 mm, which is the same as in the cooling device 1; i.e., the coolingdevice 1 of the working example and the cooling device 7 of thecomparative conventional example have the same amount of area thermallyconnecting to the heat-generating element (not shown). Due to the above,the comparative conventional cooling device 7 was more restricted in thenumber of heat pipes than the cooling device 1 of the working example,and it was necessary to flatten the shape of the heat pipes or the liketo even slightly increase the number of heat pipes.

The thermal resistance values of the working example and comparativeexample were measured with input heat quantity from each heat-generatingelement at 80 W and air volume of the cooling air supplied to theheat-radiating fins at 35 cfm. The measurement results are shown in FIG.18.

As shown in FIG. 18, in the working example, it was possible to reducethe thermal resistance of the heat-receiving area of the cooling device1 (i.e., from the heat-generating element [not shown] connected to thefirst cover 31 to the middle section of the first heat pipes 11 in thelengthwise direction) to 0.066° C./W and to reduce the thermalresistance of the heat-radiating area of the cooling device (from themiddle of the first heat pipes 11 in the lengthwise direction to the airbetween the first heat-radiating fin group 22, second heat-radiating fingroup 24, and third heat-radiating fin group 26) to 0.052° C./W.Furthermore, in the working example, it was possible to reduce the totalthermal resistance of the cooling device 1 (i.e., from the firstheat-generating element to the air between the first heat-radiating fingroup 22, second heat-radiating fin group 24, and third heat-radiatingfin group 26) to 0.118° C./W.

In contrast, in the comparative example, the thermal resistance of theheat-receiving area of the conventional cooling device 7 (i.e., from theheat-generating element [not shown] connected to the first cover 731 tothe middle section of the flat-type heat pipes 711 in the lengthwisedirection) was 0.073° C./W and the thermal resistance of theheat-radiating area of the cooling device (from the middle of theflat-type heat pipes 711 in the lengthwise direction to the air betweenthe first heat-radiating fin group 722 and second heat-radiating fingroup 724) was 0.075° C./W, which were markedly steep increases comparedto the working example. Furthermore, in the comparative example, thetotal thermal resistance of the conventional cooling device 7 (i.e.,from the first heat-generating element to the air between the firstheat-radiating fin group 722 and second heat-radiating fin group 724)was 0.148° C./W, which was a markedly steep increase compared to theworking example. In this manner, in the working example, the thermalresistance value of the heat-receiving area was reduced by approx. 10%and the heat-radiating area by approx. 30%, for a total reduction in thethermal resistance value of approx. 20% as compared to the comparativeexample.

In the working example, unlike in the comparative example, it is notnecessary to have specialized heat pipes thermally connected to theheat-generating elements or to flatten the heat pipes and arrange thepipes such that the flat sections face and are adjacent to one another;thus, thermal connectivity with the heat-generating elements wasimproved, and this is thought to have made it possible to reduce thethermal resistance values. Moreover, in the working example, the firstheat pipes 11 and second heat pipes 13 overlap each other in a plan viewand bottom view, and thus it is possible to increase the number of heatpipes and greatly increase the contact area between the heat pipes andthe heat-radiating fins; this is thought to have made it possible toreduce the thermal resistance values. In addition, in the workingexample, because the first heat pipes 11 and second heat pipes 13overlap each other in a plan view and bottom view, it was possible toreduce the dimensions of the heat-radiating fins in the heightdirection, and the heat-dissipating efficiency of the heat-radiatingfins was improved as a result; this is thought to have made it possibleto reduce the thermal resistance values.

The cooling device of the present invention is applicable to a widevariety of fields, but because it is possible to ensure the dimensionsof the heat sink in the lengthwise direction while reducing thedimensions of the heat pipes in the long-axis direction, the coolingdevice of the present invention is particularly valuable in the coolingfield for heat-generating elements such as calculation elements providedin a server, for example.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover modifications and variationsthat come within the scope of the appended claims and their equivalents.In particular, it is explicitly contemplated that any part or whole ofany two or more of the embodiments and their modifications describedabove can be combined and regarded within the scope of the presentinvention.

What is claimed is:
 1. A cooling device, comprising: a firstheat-radiating fin group having a plurality of first heat-radiating finsthat are arranged parallel to each other in a first direction; a secondheat-radiating fin group having a plurality of second heat-radiatingfins that are arranged parallel to each other in said first direction,the first heat-radiating fin group superimposing the secondheat-radiating fin group; a third heat-radiating fin group having aplurality of third heat-radiating fins that are arranged parallel toeach other in said first direction, the second heat-radiating fin groupsuperimposing the third heat-radiating fin group; one or more of firstheat pipes, one end of each first heat pipe being configured to bethermally connected to a first heat-generating element, another end ofeach first heat pipe being thermally connected to the first and secondheat-radiating fin groups; and one or more of second heat pipes, one endof each second heat pipe being configured to be thermally connected to asecond heat-generating element, another end of each second heat pipebeing thermally connected to the second and third heat-radiating fingroups, wherein said another end of each of the first heat pipes isinserted between the first heat-radiating fin group and the secondheat-radiating fin group and has a bending part in the inserted anotherend so that respective inserted another ends of said one or more offirst heat pipes altogether span a substantially entirety of a planararea between the first heat-radiating fin group and the secondheat-radiating fin group, and are thermally connected to the first andsecond heat-radiating fin groups, wherein said another end of each ofthe second heat pipes is inserted between the second heat-radiating fingroup and the third heat-radiating fin group and has a bending part inthe inserted another end so that respective inserted another ends ofsaid one or more of second heat pipes altogether span a substantiallyentirety of a planar area between the second heat-radiating fin groupand the third heat-radiating fin group, and are thermally connected tothe second and third heat-radiating fin groups, and wherein said anotherends of the one or more of first heat pipes are positioned above saidanother ends of the one or more of the second heat pipes.
 2. A coolingdevice, comprising: a first heat-radiating fin group having a pluralityof first heat-radiating fins that are arranged parallel to each other ina first direction; a second heat-radiating fin group having a pluralityof second heat-radiating fins that are arranged parallel to each otherin said first direction, the first heat-radiating fin groupsuperimposing the second heat-radiating fin group; one or more of firstheat pipes, one end of each first heat pipe being configured to bethermally connected to a first heat-generating element, another end ofeach first heat pipe being thermally connected to the first and secondheat-radiating fin groups; and one or more of second heat pipes, one endof each second heat pipe being configured to be thermally connected to asecond heat-generating element, another end of each second heat pipebeing thermally connected to the second heat-radiating fin group,wherein said another end of each of the first heat pipes is insertedbetween the first heat-radiating fin group and the second heat-radiatingfin group and has a bending part in the inserted another end so thatrespective inserted another ends of said one or more of first heat pipesaltogether span a substantially entirety of a planar area between thefirst heat-radiating fin group and the second heat-radiating fin group,and are thermally connected to the first and second heat-radiating fingroups, wherein said another end of each of the second heat pipes isinserted into a bottom portion of the second heat-radiating fin groupand has a bending part in the inserted another end so that respectiveinserted another ends of said one or more of second heat pipesaltogether span a substantially entirety of a planar area of the bottomportion of the second heat-radiating fin group, and are thermallyconnected to the second heat-radiating fin groups, and wherein saidanother ends of the one or more of first heat pipes are positioned abovesaid another ends of the one or more of the second heat pipes.
 3. Acooling device, comprising: a first heat-radiating fin group having aplurality of first heat-radiating fins that are arranged parallel toeach other in a first direction; a second heat-radiating fin grouphaving a plurality of second heat-radiating fins that are arrangedparallel to each other in said first direction, the first heat-radiatingfin group superimposing the second heat-radiating fin group; one or moreof first heat pipes, one end of each first heat pipe being configured tobe thermally connected to a first heat-generating element, another endof each first heat pipe being thermally connected to the firstheat-radiating fin group; and one or more of second heat pipes, one endof each second heat pipe being configured to be thermally connected to asecond heat-generating element, another end of each second heat pipebeing thermally connected to the first and second heat-radiating fingroups, wherein said another end of each of the first heat pipes isinserted into a top portion of the first heat-radiating fin group andhas a bending part in the inserted another end so that respectiveinserted another ends of said one or more of first heat pipes altogetherspan a substantially entirety of a planar area of the top portion of thefirst heat-radiating fin group, and are thermally connected to the firstheat-radiating fin group, wherein said another end of each of the secondheat pipes is inserted between the first heat-radiating fin group andthe second heat-radiating fin group and has a bending part in theinserted another end so that respective inserted another ends of saidone or more of second heat pipes altogether span a substantiallyentirety of a planar area between the first heat-radiating fin group andthe second heat-radiating fin group, and are thermally connected to thefirst and second heat-radiating fin groups, and wherein said anotherends of the one or more of first heat pipes are positioned above saidanother ends of the one or more of the second heat pipes.
 4. The coolingdevice according to claim 1, wherein said second heat-generating elementis designed to be located closer to said superimposed first, second andthird heat-radiating fin groups than said first heat-generating element,and said one ends of the one or more of second heat pipes are positionedcloser to said superimposed first, second and third heat-radiating fingroups than said one ends of the one or more of the first heat pipes. 5.The cooling device according to claim 2, wherein said secondheat-generating element is designed to be located closer to saidsuperimposed first and second heat-radiating fin groups than said firstheat-generating element, and said one ends of the one or more of secondheat pipes are positioned closer to said superimposed first and secondheat-radiating fin groups than said one ends of the one or more of thefirst heat pipes.
 6. The cooling device according to claim 3, whereinsaid second heat-generating element is designed to be located closer tosaid superimposed first and second heat-radiating fin groups than saidfirst heat-generating element, and said one ends of the one or more ofsecond heat pipes are positioned closer to said superimposed first andsecond heat-radiating fin groups than said one ends of the one or moreof the first heat pipes.
 7. The cooling device according to claim 1,wherein a direction of said insertion of said another ends of said oneor more of first heat pipes and said another end s of said one or moreof second heat pipes is angled with respect to the first direction in aplan view.
 8. The cooling device according to claim 1, wherein adirection of said insertion of said another ends of said one or more offirst heat pipes and said another end s of said one or more of secondheat pipes is right-angled with respect to the first direction in a planview.
 9. The cooling device according to claim 1, wherein said one ormore of first heat pipes are provided in a plurality in parallel to oneanother, and said one or more of second heat pipes are provided in aplurality in parallel to one another.
 10. The cooling device accordingto claim 2, wherein said one or more of first heat pipes are provided ina plurality in parallel to one another, and said one or more of secondheat pipes are provided in a plurality in parallel to one another. 11.The cooling device according to claim 3, wherein said one or more offirst heat pipes are provided in a plurality in parallel to one another,and said one or more of second heat pipes are provided in a plurality inparallel to one another.
 12. The cooling device according to claim 9,wherein at least one of the first heat pipes overlaps at least a portionof at least one of the second heat pipes in a plan view.
 13. The coolingdevice according to claim 9, wherein none of the first heat pipesoverlaps any of the second heat pipes in a plan view.
 14. The coolingdevice according to claim 9, wherein said inserted another ends of thefirst heat pipes are arranged in a left-right symmetric manner in saidplanar area with said first direction being the left-right direction.15. The cooling device according to claim 9, wherein said insertedanother ends of the second heat pipes are arranged in a left-rightsymmetric manner in said planar area with said first direction being theleft-right direction.
 16. The cooling device according to claim 1,wherein at least some of said first heat-radiating fins of the firstheat-radiating fin group have a cutout at a bottom part thereof toaccommodate said another ends of said one or more of first heat pipes.17. The cooling device according to claim 1, wherein at least some ofsaid third heat-radiating fins of the third heat-radiating fin grouphave a cutout at a top part thereof to accommodate said another ends ofsaid one or more of second heat pipes.
 18. The cooling device accordingto claim 1, wherein at least some of said second heat-radiating fins ofthe second heat-radiating fin group have a cutout at a bottom partthereof to accommodate said another ends of said one or more of secondheat pipes.
 19. The cooling device according to claim 1, furthercomprising either or both of a first heat-receiving plate and a secondheat-receiving plate, said first heat-receiving plate being attached toeach of said one ends of said one or more of first heat pipes so as toconvey heat from the first heat-generating element to said one ends ofsaid one or more of first heat pipes, and said second heat-receivingplate being attached to each of said one ends of said one or more ofsecond heat pipes to convey heat from the second heat-generating elementto said one ends of said one or more of second heat pipes.
 20. Thecooling device according to claim 1, wherein said another ends of saidone or more of first heat pipes are flattened in said planar area intowhich said another ends are inserted, and said another ends of said oneor more of second heat pipes are flattened in said planar area intowhich said another ends are inserted.